[lldb][NFC] Define DWARFDIE::children out-of-line instead of using template magic

[teemperor]

Summary

As pointed out by David in D103172 (thanks!)

[teemperor]

Actually, I just defined this in the source file. The child_iterator constructor anyway has to call GetFirstChild so I don't think we gain a lot by having this in the header.

[dblaikie]

Sounds good

lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.h

public:
   DWARFDIE
   GetAttributeValueAsReferenceDIE(const dw_attr_t attr) const;
 
   bool GetDIENamesAndRanges(const char *&name, const char *&mangled,
                             DWARFRangeList &ranges, int &decl_file,
                             int &decl_line, int &decl_column, int &call_file,
                             int &call_line, int &call_column,
                             lldb_private::DWARFExpression *frame_base) const;
+
   /// The range of all the children of this DIE.
-  ///
-  /// This is a template just because child_iterator is not completely defined
-  /// at this point.
-  template <typename T = child_iterator>
-  llvm::iterator_range<T> children() const {
-    return llvm::make_range(T(*this), T());
-  }
+  llvm::iterator_range<child_iterator> children() const;
 };
 
 class DWARFDIE::child_iterator
     : public llvm::iterator_facade_base<DWARFDIE::child_iterator,
                                         std::forward_iterator_tag, DWARFDIE> {
   /// The current child or an invalid DWARFDie.
   DWARFDIE m_die;
 

lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp

bool DWARFDIE::GetDIENamesAndRanges(
     lldb_private::DWARFExpression *frame_base) const {
   if (IsValid()) {
     return m_die->GetDIENamesAndRanges(
         GetCU(), name, mangled, ranges, decl_file, decl_line, decl_column,
         call_file, call_line, call_column, frame_base);
   } else
     return false;
 }
+
+llvm::iterator_range<DWARFDIE::child_iterator> DWARFDIE::children() const {
+  return llvm::make_range(child_iterator(*this), child_iterator());
+}